1. Technical Field
The present invention relates to a process and apparatus for casting a metal strip with laterally extending lugs.
2. Background Art
The conventional process for casting a strip with laterally extending lugs involves the following steps:
casting molten metal at the inlet of a molding zone, the bottom of the molding zone being formed by the upper run or surface of a moving endless belt and the sidewalls being formed by a first and a second moving endless sidedam, that move with the belt from the inlet to the outlet of the molding zone and that return outside the molding zone from the outlet to the inlet, each of these sidedams being composed of an endless strap and of a multiplicity of blocks strung thereon, some of these blocks forming lug molding pockets, the height of which are lower than that of the molding zone;
extracting a cast strip with laterally extending lugs at the outlet of the molding zone;
detecting the passage of lug molding pockets or of blocks forming these pockets on each sidedam; and
correcting the difference between the temperature of the first and second sidedams so as to change the advancing speed of at least one of these dams, a warmer sidedam moving slower than a colder sidedam, if an unwanted lag is found between the molding pockets of the first sidedam and those of the second sidedam.
Such process is described in Belgian Pat. No. 870,907, (U.S. Pat. No. 4,150,711). In this known process, the passage of lug molding pockets or of lugs formed in these pockets is detected at a determined place, measures are taken as a function of the detected lag and one waits until these sidedams have made a complete revolution to check at the same place if the measures taken at the beginning of the revolution gave the expected synchronization of the revolution gave the expected synchronization of the sidedams.
The present inventors have found that no satisfying synchronization of the sidedams can be reached in this way. Moreover, this known process provides only cooling means to modify the difference between the temperature of the sidedams; hence no intervention is possible when any lag occurs at the beginning of a casting operation, since at that moment the sidedams are still cold, and no sufficient intervention is possible when an important lag occurs later on, when the sidedams are already warm. There is even a risk of introducing a wet sidedam in the molding zone. In this known process, lug molding pockets are formed by means of blocks, the bottom side of which, i.e. the side adjacent to the aforementioned belt in the molding zone, has a Tee slot in which the aforementioned strap is located. It has been found that such blocks quickly deteriorate.